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Brown catfish may be threat to Pemberton waters



An invasive fish native to the southern United States is making its presence felt in Pemberton waters.

Observers of wildlife in the Pemberton Valley have seen traces of ictalurus nebulosis , better known as a brown bullhead or a brown catfish, in waters such as the Arn Canal and One Mile Lake. They prefer warmer waters but they can adapt to other temperatures.

Hugh Naylor, a longtime Pemberton resident and former manager of a salmon hatchery on the Birkenhead River, said he first trapped a bullhead in the late '80s after first noticing it in One Mile Lake.

"In the past, when One Mile Lake would become dry in the summer with no inflow, it would become very, very warm and tepid," he said in an interview. "Under those conditions, this little catfish could be the only thing that would survive in that water."

Naylor isn't certain of the impact the fish are having on aquatic life native to Pemberton but he said they've been known to eat other fish eggs.

"They will dig in the gravel for eggs, for salmon eggs and the other ones," he said. "It's not the only fish that eats eggs, but it would have a little bit of an impact but I don't know how serious it would be."

Veronica Woodruff, an education coordinator with the Department of Fisheries and Oceans and a member of Stewardship Pemberton, said the bullhead could be impacting coho salmon when they swim in the same waters.

"I think there'll be definitely some competition in those warmer water foraging areas. The main fish that would be affected... you could assume that the fish that would be most affected would be a coho salmon," she said.

"Those are the systems that coho are mainly using, One Mile Lake and Arn Canal. You have small fry living there a full year before going to the ocean.

"They're going to be looking for food, not only competing with them but also a great snack for (bullhead). You can assume that coho populations are most at risk from being affected by that."

Woodruff said the bullhead could also affect the young of species like salamanders and frogs that are native to Pemberton. They'll eat the same bugs and they'll even eat the young of those species.

"They actually eat the young of the toads and the frogs and the salamanders," she said. "You can imagine when you get a tadpole mass, all the frogs march out, that would be a buffet for a bullhead."

Naylor said the fish is native to southern waters such as in the state of Louisiana. He doesn't know how it got to Pemberton but he suspects it got there through "aquarium hopping." Naylor himself trapped one and stuck it in an aquarium, finding out soon after that he didn't have to take care of it as he would other fish.

"In an aquarium you have to supply a little bit of oxygen, but with this aquarium I didn't do a thing to it," he said. "The whole aquarium just became tepid, it would eat anything I fed it. After a few months it was just basically swimming around in its own poop.

"That's how tolerant they are of those sort or conditions. That's basically how they get distributed, by people keeping them in aquariums, then after a few months they get tired of looking at them and they empty them into the nearest lake. All they need is a boy and a girl and they're away."

They have a distinctive habit when nursing their young. They herd them around like "playschool kids," according to Naylor, corralling schools of their young from underneath so that they look like big balls of catfish rolling through the streams.

In the winter the fish can adapt to colder water. They simply hibernate, digging themselves into the mud at the base of a lake to sleep through the season. Then they wake up again in the spring and go on their way.

One method that's previously been used to take care of invasive species in lakes has involved the B.C. Ministry of Environment poisoning an entire lake and killing everything inside it.

Naylor isn't sure whether the Ministry still does that but nevertheless explained it as a "classical" way that the ministry took care of such species. He didn't, however, suggest that that happen in Pemberton.